bug#52157: CC Mode 5.35.1 (Profiler-Report); Objective C support extremely slow

Hello, Po.

On Sun, Nov 28, 2021 at 16:11:15 +0800, Po Lu via CC-Mode-help wrote:
> Package: cc-mode

> Emacs  : GNU Emacs 29.0.50 (build 358, x86_64-pc-linux-gnu, GTK+ Version 3.24.30, cairo version 1.17.4)
>  of 2021-11-28
> Package: CC Mode 5.35.1 (Profiler-Report)
> Buffer Style: nil
> c-emacs-features: (pps-extended-state col-0-paren posix-char-classes gen-string-delim gen-comment-delim syntax-properties 1-bit)

> Open src/nsterm.m from Emacs master, and immediately go to line 603.

> Once you try to move around after going to line 603, Emacs will lock up
> and later become extremely slow.

Yes, I see this behaviour, too.  Thanks for the report!

It seems very similar to a bug which afflicted C++ Mode earlier on this
month.  The symptoms there were the same - 100% CPU usage, but no total
lock-up; it is still possible, though sluggish, to switch frames, for
example.

I'll look at it.

[ .... ]

-- 
Alan Mackenzie (Nuremberg, Germany).